I came upon this epiphany via Google search and found this sticky thread by Otto42. If you look down at number 3:

3. Update your Adobe Flash to the latest version (esp you Linux users!): Flash.
NOTE: NOT TO VERSION 10. The new Flash version 10 is incompatible. The latest version 9 of Flash is what you want. There will likely NOT be a fix for this any time soon, since the problem is actually with Flash 10 itself. Stick with Flash 9 for the time being.

therein, lies the answer.

So now how does one roll back to Flash Player 9? A Google search produced this result on MacNN Forums with a solution by Art Vandelay. He suggested deleting the Flash Player 10 plugin and using the Mac OS X 10.5.5 software update (file size: 601MB) which includes Flash Player 9.

2008-11-01 UPDATE: So how to roll back to Flash Player 9 is easy. First delete the flash player plugins by going to /Library/Internet Plug-Ins/ and delete Flash Player.plugin, flashplayer.xpt and anything else that says Flash Player. Download the Mac OS X 10.5.5 software update and run it again. It will ask you to restart your computer and after restart, open up FireFox and load up http://www.adobe.com/products/flash/ and right click on the flash movie, at the bottom it should say “About Adobe Flash Player 9″.